The invention relates to a tool coupling between two coupling parts, in particular between a cutting head and a carrier of a rotary tool with the features of the preamble of claim 1. The invention further relates to a coupling part for such a tool coupling.
A tool coupling of this type can be gleaned from EP 1 476 269 B1, for example. A rotary tool is described therein as a drill, which is designed as what is known as a modular rotary tool. This rotary tool extends in an axial direction along an axis of rotation and comprises two coupling parts, namely a carrier and a cutting head that is attached to the carrier so as to be interchangeable. For this purpose, the carrier usually comprises on its end surface two opposite fastening webs which are separated from each other by way of chip flutes and by way of which a pin receptacle is delimited. A coupling pin of the cutting head is inserted into this pin receptacle. This is carried out by rotating the cutting head around the axis of rotation relative to the carrier. During this rotation, a clamping connection is formed between clamping sections of the cutting head that correspond to one another and the carrier, so that the two coupling parts are preferably exclusively held together in a clamping manner. Preferably, no additional fastening media, such as screws or the like, are therefore typically arranged there.
In the tool coupling found in EP 1 476 269 B1, the pin receptacle has a circular cross section, and the coupling pin has a slightly elliptical cross section. As a result of the elliptical cross section, when the coupling pin is inserted, it initially has some play in the pin receptacle. The coupling pin is usually inserted by introducing the coupling pin axially into the pin receptacle. During the subsequent turning of the cutting head, the coupling pin is clamped into the pin receptacle as a result of the elliptical cross section.
A reliable clamping can be achieved by way of the elliptical cross section. However, as a result of the elliptical cross section, only a linear type of contact is effected in forming the press fit. Furthermore, high dimensional stability is required since a defined clamping force is only reached at the intended final position.